1. Field of the Invention
The present invention relates to an object-displacement detector and a system for controlling an object-displacement.
2. Description of the Related Art
In order to realize a size reduction of the semiconductor device, it is necessary to realize a highly sensitive detection to an extremely small displacement in the atomic order, for the purpose of controlling the displacement based on the detection result. A piezoelectric device may be used for actuating the object to cause a small displacement thereof. An actual displacement is inter-related in non-linearity with an applied voltage.
The above issue of using the piezoelectric device is caused by the non-linearity between the actual displacement and the applied voltage. As long as the actual displacement is detected based on the applied voltage to the piezoelectric device, it is difficult to detect the displacement without any influence of the non-linearity,
Further, it has been known to utilize an optical interference between the object and a reference mirror. This method has a disadvantage in the non-linearity between the detected displacement and the actual displacement, and also another disadvantage in the correspondence of a single detected displacement to plural actual displacements.
Furthermore, it has also been known to utilize a variation in optical quantity upon shielding the light for detecting the displacement. This method has still another disadvantage in difficulty to detect a slight displacement.
In the above circumstances, the development of a novel object-displacement detector free from the above problems is desirable.
Accordingly, it is an object of the present invention to provide a novel object-displacement detector free from the above problems.
It is a further object of the present invention to provide a novel object-displacement detector having a simple structure with a single optical axis.
It is a still further object of the present invention to provide a novel object-displacement control system free from the above problems.
It is yet a further object of the present invention to provide a novel object-displacement control system utilizing a novel object-displacement detector having a simple structure with a single optical axis.
The present invention provides an object-displacement detector comprising: a mirror having a curved surface, and said mirror being fixed to an object; a light emitting device for emitting a light; a photo-detector having plural light-receiving regions which are divided in two-dimensional space; and a single optical system having a single optical axis for guiding said emitted light to said mirror and guiding a refracted light from said mirror to said photo-detector for detecting an intensity distribution of said reflected light.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.